System and method for improving suspension performance of lower suspension type high-temperature superconducting magnetic suspension

Abstract

The invention provides a system and method for improving suspension performance of lower suspension type high-temperature superconducting maglev, and relates to the technical field of maglev trains, the system comprises a track foundation, a permanent magnet track and a low-temperature container, and the permanent magnet track is fixedly arranged on the lower surface of the track foundation; the low-temperature container is arranged below the permanent magnet track, the end, away from the permanent magnet track, of the low-temperature container is fixedly connected with the maglev train, the low-temperature container and the permanent magnet track interact through a magnetic field, suspension and guiding of the maglev train are achieved, and a telescopic magnetism gathering mechanism is arranged in the low-temperature container and fixedly connected with the bottom of the inner side of the low-temperature container. According to the system, the liquid nitrogen and the superconducting block in the low-temperature container are reasonably configured, the adjustment of the telescopic magnetism gathering mechanism is combined, the initial magnetic flux density distribution is optimized, the internal magnetic flux density and the current density can be enhanced in a larger range, the utilization efficiency of a magnetic field is improved, and the suspension force and the guiding force are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of maglev trains, and in particular, to a system and method for improving the levitation performance of a lower-suspended high-temperature superconducting maglev. Background Art

[0002] Due to its advantages such as no mechanical friction, self-stability, and low energy consumption, high-temperature superconducting maglev technology has been widely used in fields such as maglev transportation and logistics. Currently, maglev systems mainly adopt three levitation forms: upper-levitation, side-levitation, and lower-levitation. Among them, the upper-levitation form has been successfully applied to many engineering practices due to its large levitation force; the side-levitation form has attracted attention for its excellent guiding performance; the lower-levitation form is particularly suitable for applications in high-density areas because its structural design saves ground space. However, the lower-levitation system has the problem of insufficient load-bearing capacity, which severely restricts its popularization and use in actual engineering. The magnitude of the levitation force of the lower-levitation mainly depends on the size of the field-cooling gap and the initial magnetic flux density. Traditional field-cooling methods usually enhance the levitation force by reducing the field-cooling gap, but due to the limitations of cooling conditions and device design, the feasibility of further reducing the field-cooling gap is relatively low.

[0003] Based on the disadvantages of the existing technology, there is an urgent need for a system and method for improving the levitation performance of a lower-suspended high-temperature superconducting maglev. Summary of the Invention

[0004] The purpose of the present invention is to provide a system and preparation method for improving the levitation performance of a lower-suspended high-temperature superconducting maglev to solve the above problems. To achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0005] In a first aspect, the present application provides a system for improving the levitation performance of a lower-suspended high-temperature superconducting maglev, including: an orbital foundation, a permanent magnet track, and a cryogenic container. The permanent magnet track is fixedly arranged on the lower surface of the orbital foundation; the cryogenic container is arranged below the permanent magnet track, and the end of the cryogenic container far from the permanent magnet track is fixedly connected to the maglev train. The cryogenic container and the permanent magnet track interact through a magnetic field to achieve the levitation and guiding of the maglev train. A telescopic magnetic concentrating mechanism is arranged in the cryogenic container and is fixedly connected to the inner bottom of the cryogenic container.

[0006] Furthermore, the cryogenic container further includes a housing and superconducting bulk materials. The housing is filled with liquid nitrogen, and the superconducting bulk materials are fixedly arranged on the end face of the housing close to the permanent magnet track. The telescopic magnetic concentrating mechanism adjusts the telescopic stroke to approach or move away from the superconducting bulk materials.

[0007] Further, the telescopic magnetic concentrating mechanism includes a telescopic driving device and silicon steel sheets. The housing of the telescopic driving device is fixedly arranged at the bottom of the housing body. The telescopic rod of the telescopic driving device is fixedly connected to the silicon steel sheets. The silicon steel sheets and the superconducting bulk material are arranged parallel to each other and both are arranged in the horizontal direction.

[0008] Further, a first projection area is formed on the silicon steel sheet when the silicon steel sheet is projected vertically. The area of the first projection area is less than or equal to the area of the silicon steel sheet, and the first projection area is completely within the contour range of the silicon steel sheet.

[0009] Further, when the telescopic driving device is in the maximum telescopic stroke state, the gap between the silicon steel sheet and the permanent magnet track is 5 mm.

[0010] Further, the permanent magnet track is composed of NdFeB magnets arranged in a Halbach array.

[0011] Further, the superconducting bulk material is made of YBa2Cu3O7 superconducting material.

[0012] Further, the size of the superconducting bulk material is 64×32×13 mm.

[0013] Further, the outer shell of the cryogenic container is made of heat-insulating material.

[0014] In a second aspect, the present application provides a method for improving the suspension performance of a lower-suspended high-temperature superconducting maglev, including:

[0015] Obtaining a first control command, where the first control command includes a command for controlling the maglev train to perform field cooling operation;

[0016] In response to the first control command, sending a second control command, where the second control command includes using an external force to adjust the distance between the cryogenic container and the permanent magnet track to a preset field cooling gap position;

[0017] After detecting that the cryogenic container is in place, sending a third control command, where the third control command includes a command for driving the telescopic magnetic concentrating mechanism to push to the bottom of the superconducting bulk material and maintaining a safe gap;

[0018] After detecting that the telescopic magnetic concentrating mechanism is in place, sending a fourth control command, where the fourth control command includes a command for injecting liquid nitrogen into the cryogenic container to make the liquid nitrogen level cover the superconducting bulk material and maintain a cooling state;

[0019] After detecting that the superconducting bulk material is cooled to the superconducting state, sending a fifth control command, where the fifth control command includes a command for moving the silicon steel sheet away from the superconducting bulk material through the telescopic rod to solidify the pinned magnetic flux and enter a stable suspension state.

[0020] The beneficial effects of the present invention are as follows:

[0021] The system of the present invention optimizes the initial magnetic flux density distribution by reasonably configuring liquid nitrogen and superconducting bulk materials in a cryogenic container and combining the adjustment of a telescopic magnetic focusing mechanism. It can enhance the internal magnetic flux density and current density within a larger range, not only improving the utilization efficiency of the magnetic field but also effectively enhancing the suspension force and guiding force. In addition, the method of the present invention simplifies the operation process, and through clear control commands and steps, it makes the debugging and operation of the system more efficient.

[0022] Other features and advantages of the present invention will be described in the subsequent specification, and some of them will become obvious from the specification or can be understood by implementing the embodiments of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the written specification, claims, and drawings. Brief Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic structural diagram of the standby state of the system for improving the suspension performance of a lower-suspended high-temperature superconducting maglev;

[0025] Figure 2 It is a schematic structural diagram of the system for improving the suspension performance of a lower-suspended high-temperature superconducting maglev during field cooling operation;

[0026] Figure 3 It is the magnetic field simulation result without silicon steel sheets;

[0027] Figure 4 It is the magnetic field simulation result with silicon steel sheets;

[0028] Figure 5 It is a schematic diagram of the magnetic flux density inside the superconductor of the original method (method without silicon steel sheets) and after using the present method

[0029] Figure 6 It is a schematic diagram of the current density inside the superconductor of the original method (method without silicon steel sheets) and after using the present method;

[0030] Figure 7 It is the simulation data of the improvement effect of the suspension force under different gaps;

[0031] Figure 8The suspension force test results of the present method and the original method with a field cooling gap of 5 mm;

[0032] Figure 9 The suspension force test results of the present method and the original method with a field cooling gap of 15 mm.

[0033] Markings in the figure: 1. Track foundation; 2. Permanent magnet track; 3. Cryogenic vessel; 31. Telescopic magnetic concentrating mechanism; 311. Telescopic driving device; 312. Silicon steel sheet; 32. Shell; 33. Superconducting bulk material. Specific embodiments

[0034] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations. Thus, the detailed description of the embodiments of the present invention provided herein is not intended to limit the scope of the claimed invention, but is merely representative of selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of the present invention.

[0035] It should be noted that: like reference numerals and letters denote like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Also, in the description of the present invention, terms such as "first", "second", etc. are used only for descriptive distinction and cannot be construed as indicating or implying relative importance.

[0036] Embodiment 1:

[0037] As Figure 1 and Figure 2As shown in the figure, this embodiment provides a system for improving the levitation performance of a lower-suspended high-temperature superconducting maglev train. It includes a track foundation 1, a permanent magnet track 2, and a cryogenic container 3. The track foundation 1 is a supporting structure for the permanent magnet track 2 and can be the lower surface of a bridge or the lower surface of a roof, etc. The permanent magnet track 2 is fixedly arranged on the lower surface of the track foundation 1, and the permanent magnet track 2 provides a necessary magnetic field to support the levitation and guiding functions of the train. The cryogenic container 3 is arranged below the permanent magnet track 2, and its main function is to accommodate superconducting materials and maintain them in a superconducting state. The end of the cryogenic container 3 far from the permanent magnet track 2 is fixedly connected to the maglev train. The cryogenic container 3 interacts with the permanent magnet track 2 through the magnetic field to achieve the levitation and guiding of the maglev train. A telescopic magnetic focusing mechanism 31 is arranged inside the cryogenic container 3 to achieve the focusing and adjustment of the magnetic field during the field cooling process. The telescopic magnetic focusing mechanism 31 is fixedly connected to the inner bottom of the cryogenic container 3 and can adjust the distance from the superconducting bulk 33 as needed, thereby optimizing the utilization efficiency of the magnetic field.

[0038] Preferably, the cryogenic container 3 further includes a housing 32 and a superconducting bulk 33. Liquid nitrogen is filled inside the housing 32 to ensure that the superconducting bulk 33 remains in a superconducting state during the cooling process. The superconducting bulk 33 is fixedly arranged on the end face of the housing 32 close to the permanent magnet track 2 and can effectively interact with the magnetic field between the permanent magnet track 2, thereby realizing the levitation and guiding functions. The telescopic magnetic focusing mechanism 31 adjusts the telescopic stroke to approach or move away from the superconducting bulk 33. This design not only improves the magnetic flux aggregation ability but also can adjust the working state of the superconductor according to actual needs, thereby effectively improving the levitation performance and guiding ability of the lower-suspended high-temperature superconducting maglev system.

[0039] Preferably, the telescopic magnetic focusing mechanism 31 includes a telescopic driving device 311 and silicon steel sheets 312. The outer shell of the telescopic driving device 311 is fixedly arranged at the bottom of the housing 32. The telescopic rod of the telescopic driving device 311 is fixedly connected to the silicon steel sheets 312. The silicon steel sheets 312 and the superconducting bulk 33 are arranged parallel to each other and are both arranged in the horizontal direction. With this preferred structure, the telescopic magnetic focusing mechanism 31 can better adapt to different working conditions, improve the levitation performance and efficiency of the overall system, and thus solve the problem of insufficient load-bearing capacity faced by the lower-suspended high-temperature superconducting maglev system in practical applications.

[0040] Preferably, a first projection area is formed on the silicon steel sheets 312 when the silicon steel sheets 312 are projected along the vertical direction. The area of the first projection area is less than or equal to the area of the silicon steel sheets 312, and the first projection area is completely within the contour range of the silicon steel sheets 312. Such a design ensures that almost all the aggregated magnetic flux can pass through the superconductor.

[0041] Preferably, when the telescopic driving device 311 is in the state of maximum telescopic stroke, the gap between the silicon steel sheet 312 and the permanent magnet track 2 is 5 mm. First of all, superconductors are brittle materials and are not suitable for collision or mechanical contact. Therefore, a safety gap margin is required, such as Figure 7 as shown Figure 7 The simulation data of the suspension force improvement effect at different gaps are shown. It can be found that the suspension force improvement effect is not significant when the gap is less than 5 mm. Therefore, a gap of 5 mm can be selected to fully improve the suspension force while ensuring safety. Further, the thickness of the silicon steel sheet 312 is related to the magnetic field strength of the permanent magnet track 2. The stronger the magnetic field, the thicker the thickness required. And silicon steel has a saturation magnetic field, about 1.8 T. According to the simulation results, the magnetic field integral on the upper surface of the silicon steel of the permanent magnet track 2 is 0.0085 Wb / m. According to the saturated magnetic flux formula, 0.0085 / 1.8 = 0.0047 m. So a thickness of 5 mm is sufficient to conduct all the magnetic fields and provide a significant effect. Continuing to increase the thickness will not result in an obvious increase in the effect.

[0042] Preferably, the permanent magnet track 2 is composed of NdFeB magnets arranged in a Halbach array. The design of the Halbach array significantly enhances the magnetic field strength and uniformity of the track, which is suitable for high-efficiency maglev operation.

[0043] Preferably, the superconducting bulk 33 is made of YBa2Cu3O7 superconducting material. Its main function is to interact with the magnetic field of the permanent magnet track 2 through the pinning effect to achieve self-stable suspension.

[0044] Preferably, the size of the superconducting bulk 33 is 64×32×13 mm. Further, the combination of the three seed structure designs of the bulk can improve the flux pinning strength and significantly improve the vertical suspension force and lateral guiding force.

[0045] Preferably, the outer shell of the cryogenic container 3 is made of heat-insulating material, which can effectively reduce the evaporation of liquid nitrogen and the intrusion of environmental heat, and ensure that the superconducting bulk 33 remains in the superconducting state for a long time.

[0046] Embodiment 2

[0047] Corresponding to the above system embodiment for improving the suspension performance of the lower-suspended high-temperature superconducting maglev, this embodiment provides a method for improving the suspension performance of the lower-suspended high-temperature superconducting maglev, including steps S100 to S500:

[0048] Step S100, obtain a first control command, where the first control command includes a command for controlling the maglev train to perform field cooling operation;

[0049] It is understandable that the field cooling operation refers to the process of cooling a superconducting material to its superconducting state to achieve magnetic levitation. This command is the basis of the entire operation process, ensuring that subsequent steps can be carried out in accordance with the predetermined sequence and requirements.

[0050] Step S200: In response to the first control command, send a second control command, where the second control command includes using an external force to adjust the distance between the cryogenic container and the permanent magnet track to a preset field cooling gap position;

[0051] Among them, the external force specifically refers to a fixture or a mechanical fixing device to ensure that the gap remains unchanged during the field cooling process. The field cooling gap is usually 5 mm or 15 mm.

[0052] Step S300: After detecting that the cryogenic container is in place, send a third control command, where the third control command includes a command to drive the telescopic magnetic concentrating mechanism to push to the bottom of the superconducting block and maintain a safety gap;

[0053] Step S400: After detecting that the telescopic magnetic concentrating mechanism is in place, send a fourth control command, where the fourth control command includes a command to inject liquid nitrogen into the cryogenic container, so that the liquid nitrogen level covers the superconducting block and maintains a cooling state;

[0054] It should be explained that

[0055] Specifically, silicon steel sheet is a material with a very high magnetic permeability, and its magnetic permeability is much higher than that of air. According to the principle of the minimum magnetic circuit, the magnetic field of the permanent magnet track will pass through the silicon steel sheet close to it and then return, which makes more magnetic fields completely pass through the superconductor located in the permanent magnet track and the silicon steel sheet, so that more magnetic fluxes will be captured by the superconductor. The effect of the silicon steel sheet on magnetic field concentration and levitation force enhancement can be simulated by electromagnetic simulation. The physical equations involved in electromagnetic simulation include:

[0056] B = μ0μ r H + B r ;

[0057] Among them, B represents the magnetic induction intensity; μ0 represents the vacuum magnetic permeability; μ r represents the relative magnetic permeability of silicon steel; H represents the magnetic field strength; B r represents the remanence of the magnet, which is a typical N50 magnet in this embodiment and is 1.4 T.

[0058] Maxwell's equations:

[0059]

[0060] Among them, represents the Laplace operator; E represents the electric field strength; t represents time.

[0061] Constitutive equation of superconductor:

[0062]

[0063] Among them, E c represents the critical electric field strength; J represents the current density; J c represents the critical current density; n represents the power exponent.

[0064] Lorentz force equation:

[0065] F = ∫ V (J × B)dv;

[0066] Among them, V represents the superconductor volume space; v represents the differential volume.

[0067] The magnetic field simulation results are as Figure 3 and Figure 4 shown. As Figure 3 is the magnetic field simulation result without silicon steel sheet. It can be analyzed that in the case of not using silicon steel sheet, the dispersion of the magnetic field above the track leads to the reduction of the magnetic field utilization efficiency. This dispersed magnetic field cannot be effectively concentrated on the superconducting bulk, resulting in the magnetic flux density and current density inside the superconductor not reaching the optimal state, affecting the suspension performance and guiding ability of the lower-suspended high-temperature superconducting maglev system.

[0068] Figure 4 is the simulation result with silicon steel sheet. It can be seen that after using the silicon steel sheet, the originally dispersed magnetic field above the track is effectively concentrated, mainly concentrated in the area between the silicon steel sheet and the track, that is, the position of the superconductor. This phenomenon indicates that the introduction of the silicon steel sheet significantly enhances the focusing ability of the magnetic field, thereby increasing the magnetic flux density inside the superconductor.

[0069] Figure 5 is the schematic diagram of the magnetic flux density inside the superconductor of the original method (the method without silicon steel sheet) and after using this method, Figure 6 is the schematic diagram of the current density inside the superconductor of the original method (the method without silicon steel sheet) and after using this method; through comparison, it can be found that after adopting this method, the captured magnetic field range and intensity inside the superconductor are both significantly increased. This shows that under the action of the externally applied magnetic field, the superconductor can capture and utilize the magnetic field more effectively.

[0070] At the same time, the area where the superconductor generates superconducting current is also expanded, which directly increases the intensity of the superconducting current. According to the Lorentz force principle, the increase in the magnetic field strength and current intensity will lead to a significant enhancement of the suspension force. Therefore, after using this method, the superconductor not only increases its internal magnetic flux density and current density, but also further enhances the overall suspension force.

[0071] In summary, by optimizing the magnetic field and current distribution inside the superconductor, the present invention significantly improves the levitation performance of the lower-suspended high-temperature superconducting maglev system.

[0072] Step S500: After detecting that the superconducting bulk material is cooled to the superconducting state, send a fifth control command, where the fifth control command includes an order to move the silicon steel sheet away from the superconducting bulk material through the telescopic rod to solidify the pinned magnetic flux and enter the stable levitation state.

[0073] Further, in some other embodiments, after step S500, the levitation system is also tested. Specifically:

[0074] Remove the external force previously used to fix the height of the cryogenic container (such as loosening the clamp or releasing the mechanical fixation) to allow the system to enter the free levitation state. At this time, the superconducting bulk material achieves self-stable levitation under the magnetic field of the permanent magnet track. Adjust the height of the cryogenic container to change the working gap between the superconducting bulk material and the permanent magnet track. Use a high-precision force sensor to measure the vertical levitation force and lateral guiding force of the system and record the relevant performance data. Analyze the variation law of the levitation force of the system by adjusting different working gaps.

[0075] A comparative test was carried out using this method and the original method (the method without a silicon steel sheet), and the levitation forces of the two methods were tested. As Figure 8 shown, when the field-cooled gap FCG = 5 mm, the levitation force of this method is increased by about 32%; as Figure 9 shown, when FCG = 15 mm, the increase in the levitation force of this method reaches about 25%.

[0076] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A system for improving the suspension performance of a lower-suspended high-temperature superconducting maglev, characterized in that, Comprising: Track foundation (1); Permanent magnet track (2), which is fixedly arranged on the lower surface of the track foundation (1); And Cryogenic container (3), which is arranged below the permanent magnet track (2). The end of the cryogenic container (3) far from the permanent magnet track (2) is fixedly connected to the maglev train. The cryogenic container (3) interacts with the permanent magnet track (2) through a magnetic field to realize the suspension and guidance of the maglev train. An expansion and focusing magnetic mechanism (31) is arranged in the cryogenic container (3) and is fixedly connected to the inner bottom of the cryogenic container (3).

2. The system for improving the suspension performance of the lift-down suspension type high-temperature superconducting maglev according to claim 1, wherein: The cryogenic container (3) further includes a housing (32) and superconducting bulk materials (33). The housing (32) is filled with liquid nitrogen. The superconducting bulk materials (33) are fixedly arranged on the end face of the housing (32) close to the permanent magnet track (2). The expansion and focusing magnetic mechanism (31) approaches or moves away from the superconducting bulk materials (33) by adjusting the expansion and contraction stroke.

3. The system for improving the suspension performance of the lift-down superconducting magnetic levitation according to claim 2, wherein: The expansion and focusing magnetic mechanism (31) includes an expansion and contraction driving device (311) and silicon steel sheets (312). The housing of the expansion and contraction driving device (311) is fixedly arranged at the bottom of the housing (32). The telescopic rod of the expansion and contraction driving device (311) is fixedly connected to the silicon steel sheets (312). The silicon steel sheets (312) and the superconducting bulk materials (33) are arranged parallel to each other and are both arranged in the horizontal direction.

4. The system for improving the suspension performance of the lift-down type high-temperature superconducting maglev according to claim 3, characterized in that: When the silicon steel sheets (312) are projected vertically, a first projection area is formed on the silicon steel sheets (312). The area of the first projection area is less than or equal to the area of the silicon steel sheets (312), and the first projection area is completely within the contour range of the silicon steel sheets (312).

5. The system for improving the suspension performance of the lift-down type high-temperature superconducting maglev according to claim 3, characterized in that: When the expansion and contraction driving device (311) is in the maximum expansion and contraction stroke state, the gap between the silicon steel sheets (312) and the permanent magnet track (2) is 5 mm.

6. The system for improving the suspension performance of the lift-down superconducting magnetic levitation according to claim 1, wherein: The permanent magnet track (2) is composed of NdFeB magnets arranged in a Halbach array.

7. The system for improving the suspension performance of the lifting lower-suspended high-temperature superconducting maglev according to claim 2, wherein: The superconducting bulk materials (33) are made of YBa2Cu3O7 superconducting materials.

8. The system for improving the suspension performance of the lift-down type high-temperature superconducting maglev according to claim 7, characterized in that: The size of the superconducting bulk materials (33) is 64×32×13 mm.

9. The system for improving the suspension performance of the lift-down suspension type high-temperature superconducting maglev according to claim 1, wherein: The outer shell of the cryogenic container (3) is made of heat-insulating materials.

10. A method for improving the suspension performance of a lower-suspended high-temperature superconducting maglev, characterized in that, The method for improving the suspension performance of the lower-suspended high-temperature superconducting maglev uses the system for improving the suspension performance of the lower-suspended high-temperature superconducting maglev according to any one of claims 3-9. The method includes: Obtaining a first control command, where the first control command includes a command for controlling the maglev train to perform field cooling operation; In response to the first control command, sending a second control command, where the second control command includes using an external force to adjust the distance between the cryogenic container (3) and the permanent magnet track (2) to a preset field cooling gap position; After detecting that the cryogenic container (3) is in place, sending a third control command, where the third control command includes a command for driving the expansion and focusing magnetic mechanism (31) to push to the bottom of the superconducting bulk materials (33) and maintaining a safe gap. After detecting that the telescopic magnetic flux concentrating mechanism (31) is in place, send a fourth control command, which includes a command to inject liquid nitrogen into the cryogenic container (3) so that the liquid nitrogen level covers the superconducting bulk material (33) and maintains a cooled state; After detecting that the superconducting bulk material (33) has been cooled to the superconducting state, send a fifth control command, which includes a command to move the silicon steel sheet (312) away from the superconducting bulk material (33) through the telescopic rod to solidify the pinned magnetic flux and enter a stable levitation state.

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